When will be 15th birthday?

Considering the ENDLESS games are also stuck in Soon™hell chances are high they're trying to implement crossplay or LAN multiplayer

September.

If they weren't already working on bringing the games here the above sentence would not make any sense at all. GOG would simply not have written that at all.

So what happened? Technical problems? Unlikely, considering the games are comparatively new.

It has been coming Soon™ for around a year now.

Warhammer Fest (what used to be called the Warhammer Skulls event in previous years) will be held from April 29th to May 1st this year. That's probably the next likely release window for Dawn of War on GOG.

Sounds plausible, so let's hope for the best. (But then again I believe someone said the same about last year's Skulls event...)

Last year's Skulls event was in early June, and Dawn of War wasn't announced for coming to GOG until July 20th.

Sounds logical, but we just don't know.

Maybe someone realized that at least Rise has a online component, challenges with leaderboards and ingame currency to unlock elements for these challenges. And that can be a coffin nail for GOG releases, thanks to our 'anything with an account is DRM' community.
I am just glad that I got the Epic versions of these two games for free, so I don't have to play them on Steam.

That is correct, it had not been announced... officially.

Maybe, but the game has 7500+ votes on the community wishlist (and SteamSpy says 1-2 million copies sold on Steam), so I don't see GOG giving up a release of that magnitude, unless it's a case like having as much single-player content requiring online connection as Hitman GOTY did (which iirc was like 40%+ (but I'm willing to be corrected), which is why people rioted while they haven't over CDPR's skins).

I like what idbeholdME said about using "In the works: Dawn of War" instead of "Coming Soon".

I'm guessing EGS giving the games away, then Square Enix selling the IP. Hopefully GOG will be able to convince Embracer (and/or Crystal Dynamics, as they are now the publisher of the TR games at least on GOG) to release them here eventually, assuming the Amazon lease isn't an impediment.

If you're that desperate for something on the current status you could try to reach out to General Arcade, who, considering their frequent commissional work for GoG and SNEG are very likely the ones doing the actual heavy lifting for the Dawn of War GoG Edition too (as well as the upcoming ENDLESS Space series and Dungeon of the ENDLESS?), maybe they at least are allowed to hint at or even confirm that it's still being worked on or something.

Not necessarily "the end", from the aforementioned General Arcade website:

Ghost Porting

"Ghost Porting is a unique service provided by General Arcade.

Using newly developed techniques and tools our team can in a relatively short time port PC games to other PC stores or prepare DRM-free release
without access to the source code, just by having binaries.
In the past two years, General Arcade Ghost Ported 20+ AAA titles (Control, Deus Ex: Mankind Divided among others) from major publishers and development studios.

Supported features:

- User authentication and ownership
- Overlay
- Achievements and stats
- Leaderboards
- Language detection
- DLC detection
- Cloud saves
- Rich presence

The team will also remove all mentions of Steam from game menus and game files.
* Subject to feature availability on target platform.

Process:

- Review and analyze game binary to find all original store API calls
- Replace all original store API with appropriate target store APIs
- Clean up all original store branding
- Quality assurance

Pros:

- No need to provide source code of game
- Any game engine
- A short time of porting (around two weeks including QA)
- Only native code, no emulation or runtime manipulations

Cons:

- Currently, only singleplayer games are supported
- Currently, Windows only
- DRM protected binaries with exception of Steam CEG are not supported"

Once they bring Horizon Turbo Chase to GOG I'll happily stand corrected.